Centrifugal pumps are well known in the art and are used for many fluid pumping applications. For example, centrifugal pumps may be used to pump water from one water station to another. They may also be used in construction applications, i.e., to pump water from an excavation cite.
Occasionally, a pump may ingest solid material which can cause clogging of the pump or compromise its operation in other ways. Many times this clogging may necessitate the disassembly of the centrifugal pump in order to remove the material.
Clean-out assemblies allowing access to an impeller chamber have been used in internally self-priming, centrifugal pumps. Examples of pumps having this feature are known as “T-Series” pumps sold by The Gorman-Rupp Company. A self-priming pump having clean-out capability is illustrated in U.S. Pat. No. 3,898,014.
A clean-out assembly for another type of centrifugal pump is disclosed in co-pending U.S. provisional application Ser. No. 60/178,174, filed Jan. 26, 2000, which is hereby incorporated by reference.
In the types of pumps to which this invention pertains, an impeller is rotatable within an impeller chamber and is located adjacent a wear plate. Normally, the impeller is spaced a predetermined distance from the wear plate. This space or gap is normally referred to as “face clearance.” Excessive face clearance usually reduces the efficiency of the pump so it is desirable to maintain a predetermined clearance that is normally set at the factory. Over time, the face clearance increases due to wear in the wear plate and/or impeller. As a consequence, periodic readjustment is necessary to reset the face clearance.
In the centrifugal pumps disclosed in the above-identified U.S. Patent and U.S. provisional application, the wear plate is mounted to the clean-out assembly. The clean out assembly is normally mounted to the front of the pump, whereas a rotating assembly including the impeller, and drive shaft for the impeller, is mounted from the opposite side of the pump housing. In the past, the face clearance between the wear plate and the impeller (which forms part of the rotating assembly) was established by shimming the rotating assembly. In particular, appropriate shims were placed between the pump housing and a flange forming part of the rotating assembly. The shims determined the face clearance and were held in position by bolts that secured the flange to the housing.
In these types of pumps, the drive shaft which extends from the rotating assembly is coupled to a drive motor. If the position of the rotating assembly changes with respect to the pump housing due to a change in shims, an adjustment would also have to be made to the coupling between the drive shaft and drive motor to accommodate the change in position. Alternately, the position of the drive motor and/or pump would require changing in order to accommodate the change in position of the rotating assembly. In the past, shimming of the rotating assembly, rather than the clean-out cover assembly, was preferred because the clean-out assembly is removed quite frequently, as compared to the rotating assembly.